B.2.2.2. Visual search

Lavie and de Fockert (2005) did not find an effect of WM on attentional orienting. The WM task they used was basically mnesic, since participants just had to remember a series of 5 or 6 digits. Yet, Han and Kim (2004) showed that visual search was hampered by an executive WM load, involving manipulation of digits and letters, but not by a mnesic WM load, demanding only to remember these items. These results were confirmed in eye movement studies. Mitchell et al. (2002) evidenced an influence of an executive WM task on the accuracy in an anti-saccade task, but not on a pro-saccade task. However, the p-value of this latter comparison (p = .12; (F(3,45) = 2,05) was probably too close to the usual α-level to allow rejecting the null hypothesis confidently (as argued by Frick, 1995). And indeed, Unsworth et al. (2004) showed that WM span effects were not "restricted to the inhibitory component", but also influenced performances in the pro-saccades, suggesting that the endogenous control of attention also depended on WM. In summary, it seems that executive WM was not only necessary for resisting interference, but also for endogenously orienting the attention and / or eyes. This latter point was not predicted by the load hypotheses of Lavie (2005).